PLL CIRCUIT OPERATING BASED ON OUTPUT OF DELTA-SIGMA MODULATOR, AND OPTICAL DISK DEVICE INCLUDING PLL CIRCUIT

摘要

A PLL circuit includes a wobbling detector for detecting a wobbling signal based on reflection light of an optical disk having a wobbled track, and a VCO that an oscillation frequency of its output varies according to its input. The PLL circuit controls the VCO based on a phase error between the output of the wobbling signal and the output of the VCO. In the PLL circuit, the phase error is detected by executing an arithmetic operation to the delta-sigma modulated wobbling signal at a predetermined clock and the output of the VCO.